diff --git a/src/main/java/net/openhft/chronicle/map/NodeDiscoveryHostPortBroadcaster.java b/src/main/java/net/openhft/chronicle/map/NodeDiscoveryHostPortBroadcaster.java
index 43aa59b52..ed88341cd 100644
--- a/src/main/java/net/openhft/chronicle/map/NodeDiscoveryHostPortBroadcaster.java
+++ b/src/main/java/net/openhft/chronicle/map/NodeDiscoveryHostPortBroadcaster.java
@@ -396,10 +396,16 @@ class BytesExternalizableImpl implements BytesExternalizable {
     private ATSDirectBitSet orBitSets(@NotNull final ATSDirectBitSet source,
                                       @NotNull final ATSDirectBitSet destination) {
 
+        source.clear();
+
         // merges the two bit-sets together via 'or'
         for (int i = (int) source.nextSetBit(0); i > 0;
              i = (int) source.nextSetBit(i + 1)) {
-            destination.set(i);
+            try {
+                destination.set(i);
+            } catch (IndexOutOfBoundsException e) {
+                e.printStackTrace();
+            }
         }
 
         return destination;
diff --git a/src/test/java/net/openhft/chronicle/map/NodeDiscoveryHostPortBroadcasterTest.java b/src/test/java/net/openhft/chronicle/map/NodeDiscoveryHostPortBroadcasterTest.java
index 4bb3cfa7f..3226199c7 100644
--- a/src/test/java/net/openhft/chronicle/map/NodeDiscoveryHostPortBroadcasterTest.java
+++ b/src/test/java/net/openhft/chronicle/map/NodeDiscoveryHostPortBroadcasterTest.java
@@ -36,7 +36,12 @@ public class NodeDiscoveryHostPortBroadcasterTest extends TestCase {
         externalizable.sendBootStrap();
 
         externalizable.add(new InetSocketAddress("myhost", 8888));
+        externalizable.add(new InetSocketAddress("myOtherHost", 8888));
         externalizable.add((byte) 2);
+        externalizable.add((byte) 2);
+        externalizable.add((byte) 3);
+        externalizable.add((byte) 4);
+        externalizable.add((byte) 1);
 
         Thread.sleep(1000);
     }